Delete thumbnails alongside DB rows in all three removal paths (watcher
detect, delete-from-disk command, remove-folder command) so orphans no
longer accumulate passively.
Intercept RenameMode::Both watcher events and handle them as in-place
path updates: renames the thumbnail file to the new hash and updates the
DB row without touching the embedding, avoiding a full rebuild on move.
Falls back to thumbnail regeneration if the file rename fails.
LyAhn
ceb51f8fad